#include <bits/stdc++.h>

int ri() {
	int n;
	scanf("%d", &n);
	return n;
}

int main() {
	int q = ri();
	for (int i = 0; i < q; i++) {
		int n = ri();
		int k = ri();
		if (k == 1) {
			std::cout << n - 1 << std::endl;
		} else {
			int res = -1;
			int64_t cur = 1;
			int64_t sum = 0;
			for (; sum < n; res++) {
				sum += cur;
				cur *= k;
			}
			std::cout << res << std::endl;
		}
	}
	return 0;
}